Forced rotary-draft furnace



J. GASKlLL.

FORCED ROTARY DRAFT FURNACE.

APPLICATION men SEPT.3.1918. 1,857,494, Patented NOV. 2, 1920.

UNITED STATES J'AMES GASKILL, 0F CLEVELAND, OHIO.

FORCED ROTARY-DRAFT FURNACE.

Specification of Letters Patent.

Patented Nov. 2, 1920.

Application filed September 3, 1918. Serial No. 252.338.

To all whom it may concern Be it known that 1, JAMES GAsKrLL, a citizen of the United States, and resident of Cleveland, in the county of Cuyahoga and State of Ohio, have invented certain new and useful Improvements in Forced Rotary-Draft Furnaces, of which I hereby declare the following to be a full, clear, and exact description, such as will enable others skilled in the art to which it appertains to make and use the same. The objects of the invention are to provide an improved form of metallurgical furnace in which fuel oil or gas in connection with an air blast of superheated air is employed to obtain a high degree of temperature, which can be utilized to melt steel or iron or other metals, and to reduce refractory ores in less time than. wouldordinarily be required in the well known reducing furnaces, or can be applied to annealing and heat treating metal parts or objects such as high speed tools and dies, and milling cutters or alloyed metals or products, in the heat treatment of metals where the complete exclusion of cold air and drafts during the process is required.

The device comprises an inner combustion chamber or retort in which a crucible or mufiie containing the ore or metal products are positioned, and also includes an outer annular inclosing chamber in which the air under pressure is circulated about the combustion chamber until it absorbs a large amount of the heat generated therein, and is finally injected together with the fuel or gas through a burner tube into the combustion chamber. The invention also includes a removable cover for the combustion chamber and convenient pedal operated means for removing the same. This relieves the workman from loss of time and labor in manually handling the cover.

It further includes a releasable support or bottom for the crucible, and means for retaining the support in place.

The advantages of the releasable support are obvious, since the support can e dropped to remove slag or metal from the combustion chamber in case the crucible or mufiie should become broken. Otherwise it would be necessary to destroy the walls of the combustion chamber when it is desired to remove the charge therefrom.

The invention also includes means for giving a rotary upward movement to the air mixer, in which the air and gas are com-- ml ngled before passing to the burners. lhe mvention consists in the device hereinafter described, shown in the accompanymg drawings and specifically pointed out in the claims. In the accompanying drawings, Figure 1 1s a vertical central section of the device. F 1g. 2 1s a transverse section on line a-a F 5g. 3 (is a 1sideF elevation of the furnace at 5 re uce sca e; 1 4: is a )lan of the su for the crucible. b 1 pport In these views, A, A are the walls of a combustion chamber or retort, these walls being formed of fire brick capable of withstanding a temperature of 3000 degrees or 4000 degrees Fahrenheit. B is a cover therefor. C, C, are folding gates hinged at D, D, which retain a support preferably formed of fire brick and resting upon the gates C. Upon this support, a crucible F is mounted, removable props or supports t, Gr preventing the gates from falling until accidental breaking of the crucible makes it necessary to remove the spilled charge from the chamber A by lowering the gates. Exterior to the combustion chamber is shown an outer annular air circulating stormg and compressing chamber H, having outer and inner concentric Walls I and J respectively. Air enters this outer chamber at the bottom through. a tangentially extending pipe K. The air is taken from this annular chamber at the top through the downwardly directed pipes L, L, arranged diametrically opposite to each other, and at the lower ends of these pipes are positioned mixers. M, M, into which the fuel oil or gas is discharged and the commingled air and gas is forced by pressure through the tan gentially placed burner tubes N, N, into the combustion chamber. The tangential position of the air inlet pipe and burner tubes is preferably such as to reverse the direction of the whirling movements of the air in the outer chamber and the commingled air and gas in the combustion chamber, although this action is not essential to the operation of the furnace but is more convenient since it enables the inlet and outlet openings to be spaced farther apart in the walls of the furnace.

Since the air enters at the bottom of the outet-phamber and traverses this chamber in an .u'pward spiral direction to the outlets above,it will have passed several times about I this chamber, and since the chamber is open throughout, the pressure will be equalized therein and at both outlets, and also the temperature will be equalized throughout the chamber and maintained uniform at the outlets.

The air in the chamber H absorbs heat from ,direct contact with and radiation from the entire surface of the outer wall J of the combustion chamber A, and hence the blast can be quicklyraised to a high degree of temperature.

The hot air blast also quickly vaporizes the oil fuel and prevents deposit of carbon in the burners, thus keeping them clear. The blast also being dry, is less destructive of the crucibles and mufiies than a blast of moist cold air would be. The air under pressure can be supplied from any convenient means for producing the same, such as the blower O.

Valves P, Q and R upon the several air and gas flues control the amount of pressure therein.

The fire brick walls of the combustion chamber are increased in thickness intermediate of the ends to form a projecting zone S, having upper and lower horizontal shoulders S, S The object of the lower shoulder S is to check the immediate rise of the gas and flame and deflect it toward the crucible and prevent it from issuing directly from the central outlet opening T, in the cover. The upper shoulder S provides a chamber S in which the gas can expand before issuing from the chamber and hence retards its issue.

The support for the crucible is provided with a transverse opening E through which metal or slag can find its exit in case the crucible should become broken and discharge its contents The draft being from within will issue from this opening and prevent cold air from entering.

In this manner all outside air is excluded 7 from the furnace and a maximum degree of heat is retained within the chamber. The cover normally rests upon the top ofthe furnace and is mounted upon a plate V, which is secured to a vertical shaft V, rotatable and longitudinally movable in bearings V secured to the outer wall of the furnace. V

A pedal lever W, when pressed upon by the foot will raise the rod and cover, and a lever W secured to the rod, can then be employed to rotate the rod and remove the cover from the furnace.

The furnace can'be heated in alternative manner by injecting an atomized fuel oil into the blower through nozzle X, and forcnite periods of time without variation when the several fuel and air inlet valves are suit-- abg adjusted.

aving -described the mvention what I claim as new and desire to secure by Letters Patent is 1. A furnace for the purpose described, comprising a combustion chamber, the walls of which are formed of fire brick, an annular chamber for air, inclosing the vertical sides of said combustion chamber, an air inlet pipe, entering the lower end of the furnace, air descending outlet pipes communicating with the upper end of said air chamber, a corresponding number of fuel admission pipes, commingling chambers with which said descending air pipes and fuel admission pipes communicate, and burner tubes extending into said combustion chamber and communicating with said mixing chambers.

2. In a furnace for the purpose described, a combustion chamber, an annular air circulation chamber thereabout, means for introducing air under pressure into the lower part of said annular air chamber, gas and air mixers adjacent the lower end of said furnace, means for conductingthe air from the upper part of said annular chamber to said air and gas mixers, means for conducting fuel gas or oil to said mixers and burners for introducing the commingled air and gas into the combustion chamber.

3. In a furnace for the purpose described, a vertical combustion chamber, an annular air circulating and air pressure equalizing chamber, inclosing the sides of said chamber, means for causing rotary upwardly directed circulation of air throughout said air circulation chamber, to superheat the same, and means for commingling the air thus heated with fuel gas or oil, and burners inserted into the combustion chamber, said burners communicating with said air and gas commingling means, the wall of said combustion chamber projecting inwardly to form a shoulder underneath which said burners discharge.

4:. In a furnace in combination, a com bustion chamber, an annular air circulating chamber encircling said melting chamber, an air inlet pipe communicating with the lower end of said air circulating chamber and entering the same tangentially thereto,

air outlet pipes communicating with the upper end of said air circulating chamber, an air and gas commingling chamber adjacent to the base of said combustion chamber, said air outlet pipe communicating with said mixing chamber, means for introducing the gas to said commingling chamber and a burner tube leading from said commingling chamber and tangentially entering said combustion chamber.

5. In a furnace, a combustion chamber, the side walls of which project inwardly intermediate of its ends to form upper and lower shoulders, an external air circulation chamber encircling said melting chamber, means for providing a rotary circulation of air therein to heat the same, means for commingling said heated air with fuel, and burner tubes supplied from said commingling means and burner nozzles discharging anto said chamber below said lower shoulers.

6. In a furnace for the purpose described, a vertical combustion chamber, and an annular air circulating and air pressure equalizing chamber inclosing the sides of said chamber, a single air inlet opening entering said air chamber tangentially adjacent to its base, a plurality of an outlet 0 enings leading from said air chamber ajacent to its upper end, a corresponding number of fuel nozzles entering said chamber adjacent to its base, fuel supply pipes therefor, mixers for said pipes and air passages connecting said air outlet openings and said'mixers.

7 In a metallurgical furnace, a vertical combustion chamber, a cover for the upper end thereof, said cover havin an outlet opening, the sidewalls of said 0 amber projecting lnwardly, intermediateof its ends, the lower edge of said projection forming a shoulder for deflecting the products of combustiontoward the interior of said chamber,

the upper edge of said'projection coiiperating with said cover to form an expansion chamber in which the products of combustion are retarded from escaping from said outlet' openings. v

'8. In a metallurgical furnace, a combustion chamber provided with enlarged lower and upper extremities, an annular air cham: ber inclosing the outerwalls thereof, means for providing a rotary spiral current of air in said air chamber, a gas burnerpipe, a

mixer for gas and air on said burner pipe and connecting pipe forming a means of communication between said annular air chamber and said mixer and a burner nozzle discharging into the said enlarged lower portionof said combustion chamber.

9. In a metallurgical furnace, a combustion chamber provided with inwardly projecting shoulders adjacent its upper and lower ends, an annular air chamber inclosing the outer walls thereof, means for providing a rotary spiral current of air in said air chamber, a gas burner pipe, a mixer for gas and air on said burner pipe and connecting pipe'forming a means of communi- 1 cation between said annular air chamber and said mixer, and ,a burner nozzle communieating with said mixer and discharging into said combustion chamber underneath said lower shoulder. I

10. In a furnace, a combustion chamber, a chamber containing compressed hot air con-- centric'therewith and heated thereby, burner nozzles for said combustion chamber, fuel supplying means for said nozzles, Im'xers thereon and means for supplying air from said hot air chamber to said mixers.

11. In a furnace, a combustion chambelya burner, an air chamber adjacent thereto, and heated thereby, for containing hot air under uniform temperature and pressure, and a commingling chamber or mixer for fuel and air from said air chamber, said mixer communicating with said burner and 1 air chamber substantially as described.

12. In a furnace, a combustion chamber, a chamber containing air under pressure and heated thereby, means for causing rotation of the air-in said air chamber to e ualize the temperature and pressure therein, urner nozzles enterin said combustion chamber, a

commingling c amber for fuel and air for each burner nozzle, and spaced outlet pipes leading from the top of said air chamber to said commingling chambers, supply pipes for a fuel leadin to said commingling chambers, anda supp y pipe for air leading to the bottom of said-air chamber.

In testimony whereof I hereunto set my.

hand this 21st day 0; Au

st, 1918. S GrASKILL. In presence 'of- GEO. D. HILL, WM. M. Mormon. 

